This project involves the conduct of therapeutic clinical trials for the treatment of inherited immune deficiencies using hematopoietic stem cell transplantation. We previously reported the successful use of non-ablative conditioning to achieve successful long term engraftment and cure of CGD patients using HLA-matched sibling donors as the source of the hematopoietic stem cell graft. One of the problems with this approach was the high rate (30%) of graft failure or very low engraftment. In 2004 we performed a follow up transplant on an X-CGD child previously transplanted by us who had achieved high level donor T cell engraftment but less than 1% long term myeloid engraftment. We demonstrated successful permanent conversion to almost 100% donor chimerism in the lymphoid and myeloid lineages using conditioning with only busulfan at 10 mg/kg. This strongly supports the use of this approach to rescue low engraftment rather than using a fully myelo- and lympho-ablative conditioning regimen for such salvage therapy. We have now opened a clinical trial to treat patients with immunodeficiencies using either a matched related, matched unrelated, or cord blood product and a tolerance inducing conditioning regimen consisting of Campath 1-H and busulfan with sirolimus for graft versus host disease (GvHD) prophylaxis. For patients receiving an unrelated product, total body irradiation is also added to the regimen. To date we have transplanted a total of 43 patients, 38 of whom received an unrelated donor graft. In patients not receiving a stem cell boost we have we have seen very limited GvHD with only one patient having Grade 2 skin GvHD and three patients with Grade 1 GvHD of the gut. We have used cord blood in 3 cases. One was for a patient with P67 deficient CGD and another with the X-linked form, both of whom failed to engraft. With the first patient, the thinking was that the Campath impacted negatively with the ability of the more naive T cells in a cord blood graft preventing engraftment, and the protocol was modified to use ATG in the case of a cord blood product. However with the second graft failure in a CGD patient, we have stopped using cord blood products for these patients. This data is also correlated by results from Duke University where even with a myeloablative regimen, the engraftment rate using cord blood products in CGD patients is between 40 to 50%. The third patient to receive a cord blood graft was transplanted for X-linked Severe Combined Immunodeficiency. He was conditioned with ATG instead of Campath and is currently 7 years out with full engraftment, no evidence of graft versus host disease, and normal immune function. We now have had a total of nine deaths on the protocol. Two of the deaths were unrelated to the transplant (refusal to continue dialysis, and a accidental drug overdose). One patient developed a transfusion related acute lung injury after a platelet transfusion and three patients died from infection after developing GvHD (Klebsiella infection, adenovirus, and aspergillus brain abscess). One patient had pulmonary hemorrhage and CMV and a final patient developed HHV6 after prolonged pancytopenia after a late graft failure and stem cell boost. Despite these outcomes, our overall mortality rate has been low relative to bone marrow transplantation in general using unrelated donors. Further we have transplanted a number of patients with ongoing infections including fungal osteomyelitis of the spine and/or meninges and in some cases have used granulocyte infusions during the period of transplant-induced neutropenia with no adverse effects. To date, all patients except one with CGD transplanted with an ongoing infection have done well without any significant morbidity or mortality due to infection progression during the transplant course. Overall our results for the CGD patients in particular are especially promising with an overall survival of 32 out of 41 and an overall long term engraftment rate of 33 out of 35 evaluable. In 2014 we have transplanted 7 patients to date. Inorder to determine the outcomes of transplant for CGD in general, we have become a part of the Primary Immune Deficiency Treatment Consortium and have initiated a collaborative protocol to review the results of transplant done for CGD in North America. The protocol has now been approved and is being implemented in various centers. Finally we are preparing to being a haploidentical transplant protocol for patients with CGD who do not have an HLA matched donor, related or otherwise. Some of this work may be done in collaboration with Dennis Hickstein of the NCI and/or Andrew Gennery of Newcastle on Tyne. In related laboratory pre-clinical studies, we have been investigating the use of an adenosine A2a receptor agonist to prevent or treat graft versus host disease. Prior studies have shown that agonists specific to this receptor improve outcomes in ischemia models of tissue damage. In collaboration with the investigators at the University of Virginia who have supplied a specific agonist known as ATLe146, we tested this drug in a murine model of graft versus host disease. We have seen benefit in attenuating the onset and severity of GVHD in our F1-parental transplant model and have published this data in the Journal of Leukocyte Biology. Further studies have shown a role for T regulatory cells (Tregs) as part of the mechanism of the drugs effects. We have now established a new CRADA with Lewis and Clark Pharmaceuticals (formally Adenosine Therapeutics/PgxHealth/Forest Labs) to study other formulations of the A2a receptor agonists and have seen similar effects on T regs, both invitro and invivo, by these agonists. This data was published in the Journal of Immunology. We are now working on improving the formulation and In addition, we have found that rapamycin also works to reduce TH17 cells in our model and we are studying combination drug therapies now in our model and have evidence that rapamycin may improve engraftment when used in the context of nonmyeloablative regimens. Moreover, we have started to study these drugs in a colitis model given their benefit in GvHD of the gut. We have also started a collaboration with Gabriel Dvesklar of UHSUS to study Pregnancy Specific Glycoprotein -1 (PSG-1) as an immunomodulator and a possible therapy for GvHD. Preliminary in vitro and in vivo studies suggest some benefit but further study is needed.